No dimmers at all. These lights are designed to be used with their app to control their brightness. They require constant power on. Otherwise your main control box won't see the individual light if it's manually turned off with a switch.

Yes as long as they are compatible with the same bridge. All philips hue(16 million colors) or hue lux(white) can be controlled with the same bridge. Even the other hue products, blooms and irises are all controlled by one bridge. There are some philips products out there, like the aura, that aren't controlled by a bridge but by a remote control that comes with the lamp. I would ask Phillips hue support to be sure but most of their new LED products are clearly marked "hue" or "friends of hue" and I think that is the indicator you are looking for. I love these things because it turns something old, inefficient, and boring into something that is innovative, energy efficient, and lots of fun. It's a bit pricey but if your going from a halogen or incandescent to LEDs, the money you will save on the electric bill alone will make this purchase worthwhile. The only problem I have with this product is the app itself. It needs some work and that is why the app has such a poor rating in the app store but there is a lot of 3rd party apps and the potential is there to be great one day hopefully.

Not sure but you can use other HUE bulbs to increase the range of the bridge to your bulbs. Each bulb will piggyback on the other to increase the range of the bridge. However, you should be aware that in that case, the furthest bulb may not work (they will light up like a standard bulb but cannot be controlled from the phone app) if the ones in between are physically switched off.

I want to control my Hue lights with my iPhone6 voice control (Siri). I've asked her and she tells me she can't until I "set something up".
What do I need to set up?
My lights are functioning and the Hue app is fine but I really want to get Siri to do it.
Thanks in advance

You'll have to wait for an update in the app or IFTTT to use Siri. You can only use Siri if they take advantage of the APIs. Those APIs will be available with a iOS update, when HomeKit becomes available.

The wattage is 8w, but don't worry about that. The light output is quoted at 600lm. Bear in mind though that that would be with all the internal elements running flat out, so less with colours other than white.

Philips say the output is comparable to that of a 40w incandescent bulb.

Yes you can connect to Hub's to one network. They will behave as two different networks and some apps, including the Philips App, can support two bridges. However they will behave independently so to turn all lights off you would need to switch hubs. Each hub can support 50 lights so if you want everything in the house to act as a single lighting system you only need 1 hub.

However, as in my case, my son has his own large room with a Hue system and has it connected to IFTTT. The bridge can only connect to one IFTTT account so if you want independent control then two hub's become essential. He now has his lighting system, I have mine. All off on his iPhone does not turn off my lights and vs versa.

So in summary, it can be done, it needs to be done if you want independent My Hue/IFTTT accounts but doesn't need to be done if you want everything to act as one whole lighting system.

No. Not in Australia as far as I know. Adapters are available, however they a difficult to find locally also. You can buy them internationally from that well known internet auction site and that is how I connected some of my bulbs,